Dehumidification (air drying) in an air conditioning system is provided by the evaporator. Since the evaporator operates at a temperature below the dew point, moisture in the air condenses on the evaporator coil tubes. This moisture is collected at the bottom of the evaporator in a pan and removed by piping to a central drain or onto the ground outside.
An air conditioning system, or a standalone air conditioner, provides cooling and humidity control for all or part of a building. Air conditioned buildings often have sealed windows, because open windows would work against the system intended to maintain constant indoor air conditions. Outside, fresh air is generally drawn into the system by a vent into the indoor heat exchanger section, creating positive air pressure. The percentage of return air made up of fresh air can usually be manipulated by adjusting the opening of this vent. Typical fresh air intake is about 10%.
Natural ventilation is the ventilation of a building with outside air without using fans or other mechanical systems. It can be via operable windows, louvers, or trickle vents when spaces are small and the architecture permits. In more complex schemes, warm air is allowed to rise and flow out high building openings to the outside (stack effect), causing cool outside air to be drawn into low building openings. Natural ventilation schemes can use very little energy, but care must be taken to ensure comfort. In warm or humid climates, maintaining thermal comfort solely via natural ventilation might not be possible. Air conditioning systems are used, either as backups or supplements. Air-side economizers also use outside air to condition spaces, but do so using fans, ducts, dampers, and control systems to introduce and distribute cool outdoor air when appropriate.

So, naturally I respond with, “you don’t tell your doctor which medication to prescribe you, do you?” The point is, on the residential level, who you get to install your HVAC unit is far more important than which unit you choose.  Keep your options open and let your HVAC contractor make a few recommendations – that’s why you spent time finding a reputable contractor!
As for the price I think my review was fair in stating what value we got for what I deemed to be a slightly higher price than others might charge.  I did not take any stars off for the price, and still am not, but I am taking another star off because of Alberto's comments, which are deceptive and not the same thing he told me in person.  Alberto, I suggest you stick with the high road in the future.
My mom just received service from this company. She paid $609 to have her frion replaced. After two uses the AC stops working. A young rep comes out to the house again and notifies her that her entire AC unit and furnace need to be replace for just shy of ten grand, though when her frion was refilled she was told that her system should last another five years. When they came back to tell her how her entire system needed to be replaced, they were generous enough to offer her a $300 credit on the nearly $10,000 estimate of replacing the entire system that was working fine until they touched it. My best assumption would be that there is a mishap with the system is due to their negligence. Id suggest using another company other than these scam artists.
Without proper ventilation, carbon monoxide can be lethal at concentrations of 1000 ppm (0.1%). However, at several hundred ppm, carbon monoxide exposure induces headaches, fatigue, nausea, and vomiting. Carbon monoxide binds with hemoglobin in the blood, forming carboxyhemoglobin, reducing the blood's ability to transport oxygen. The primary health concerns associated with carbon monoxide exposure are its cardiovascular and neurobehavioral effects. Carbon monoxide can cause atherosclerosis (the hardening of arteries) and can also trigger heart attacks. Neurologically, carbon monoxide exposure reduces hand to eye coordination, vigilance, and continuous performance. It can also affect time discrimination.[15]

Don Vandervort has developed his expertise for more than 30 years, as Building Editor for Sunset Books, Senior Editor at Home Magazine, author of more than 30 home improvement books, and writer of countless magazine articles. He appeared for 3 seasons on HGTV’s “The Fix,” and served as MSN’s home expert for several years. Don founded HomeTips in 1996.

PickHVAC Tips: Oil burns dirty, so it is important to have your plenum and ducts checked to see if they should be cleaned when replacing an oil furnace. If you don’t clean the plenum and ducts when replacing the furnace, the new furnace might not run as efficiently and comfortably as possible due to restricted airflow. This can also reduce the oily smell sometimes associated with oil furnaces.
Fuses -- Anyone who has worked with electrical systems knows all about fuses and how they fail. They can burn out over time, may just be loose, or can blow out during an electrical storm or due to overload from another failed component. Of course, that's what they're supposed to do; they stop surges from going through and damaging the rest of the system. When a fuse fails, whatever system it was protecting will stop working.
CIBSE publishes several guides to HVAC design relevant to the UK market, and also the Republic of Ireland, Australia, New Zealand and Hong Kong. These guides include various recommended design criteria and standards, some of which are cited within the UK building regulations, and therefore form a legislative requirement for major building services works. The main guides are:
The cost to replace a central air conditioner is about $5,000. However, this price varies depending on the size of your home and the difficulty of the project. It can cost as much as $12,500 to replace an AC unit. The labor required to remove and dispose of the old system adds to the price. The size of your home, brand of AC unit and ductwork complexity can all raise the cost as well.

While a lot of people understand the consequences of AC problems throughout the summer, the summer comes with its own set of unique issues that require a call to the plumber, too. Whether it’s a malfunctioning sprinkler system or a sewer line backup, Service Experts can help. We’ve encountered it all, and you won’t have to worry about any of it with our 24/7/365 Emergency Plumbing Service. When you need a plumber, we are here for you. And, just like all of our other services and products, any plumbing repair or work completed by Service Experts is backed by the same 100% Satisfaction Guarantee*.
In the United States, HVAC engineers generally are members of the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE), EPA Universal CFC certified (for installation and service of CFC HVAC devices), or locally engineer certified such as a Special to Chief Boilers License issued by the state or, in some jurisdictions, the city. ASHRAE is an international technical society for all individuals and organizations interested in HVAC. The Society, organized into regions, chapters, and student branches, allows exchange of HVAC knowledge and experiences for the benefit of the field's practitioners and the public. ASHRAE provides many opportunities to participate in the development of new knowledge via, for example, research and its many technical committees. These committees typically meet twice per year at the ASHRAE Annual and Winter Meetings. A popular product show, the AHR Expo, is held in conjunction with each winter meeting. The Society has approximately 50,000 members and has headquarters in Atlanta, Georgia.
Brands like American Standard, Trane and Lennox cost the most. Goodman is the cheapest. The rest populate the middle of the spectrum. Here’s something to know: The quality among brands isn’t as great as price differences. The difference in prices reflect that some customers want “bargain” equipment to save cost and others want “premium” equipment they believe will run longer with less trouble. Therefore, each manufacturer has priced to meet consumer perception.

PickHVAC Tips: Electricity resistance heat is the most expensive heating type. You don’t want one of these unless you’re heating less than 30 days per year. The upfront cost of an electric furnace is much lower than the cost of a gas furnace. However, operating costs are two to three times higher. If winters are cold where you live, you’ll waste your upfront cost savings in just a few years of high electric bills.


Ventilation is the process of changing or replacing air in any space to control temperature or remove any combination of moisture, odors, smoke, heat, dust, airborne bacteria, or carbon dioxide, and to replenish oxygen. Ventilation includes both the exchange of air with the outside as well as circulation of air within the building. It is one of the most important factors for maintaining acceptable indoor air quality in buildings. Methods for ventilating a building may be divided into mechanical/forced and natural types.[16]
Before we get to HVAC installation prices, we will first need to briefly discuss some terms, definitions, and factors that will affect how an honest HVAC installation company determines their prices. Notice that I said honest. Unfortunately, there are dishonest people out there. There always have been, there always will be, and there is a good chance that you had an experience with such a contractor, which is what drove you to read this article. I can’t teach you how to tell if someone is honest, but I can give you the knowledge to help you decide. Take a look at How to Choose an HVAC Contractor for tips on what to look for.
These factors are included in a "Manual J" calculation. Contractors who make these calculations before recommending a size can take a couple of hours collecting the information and making the calculation. If your contractor doesn't do it, there are services that will do it for around $99. If you're feeling particularly on the ball, there are also free online calculators.

HVAC System Quality Installation Contractor Checklist -- This checklist identifies all of the steps the contractor has taken for the Energy Star Certification and identifies what work the contractor has done. If the system is later modified, this checklist can help identify what was done to proper Energy Star specifications and what was added later that may not meet the requirements.

Natural ventilation is the ventilation of a building with outside air without using fans or other mechanical systems. It can be via operable windows, louvers, or trickle vents when spaces are small and the architecture permits. In more complex schemes, warm air is allowed to rise and flow out high building openings to the outside (stack effect), causing cool outside air to be drawn into low building openings. Natural ventilation schemes can use very little energy, but care must be taken to ensure comfort. In warm or humid climates, maintaining thermal comfort solely via natural ventilation might not be possible. Air conditioning systems are used, either as backups or supplements. Air-side economizers also use outside air to condition spaces, but do so using fans, ducts, dampers, and control systems to introduce and distribute cool outdoor air when appropriate.

An air conditioner's compressor contains a refrigerant. As it works, it sends this refrigerant through the system. As warm air blows across the coil that carries this refrigerant, the heat transfers to the refrigerant (cool always absorbs warm). A fan moves the cooled air through the ducting and out of vents that lead into the rooms of your house. The refrigerant returns to the compressor where the absorbed heat is moved outside. The refrigerant is then sent through the coil once again to continue the cycle.
R-22 Freon is being phased out & isn't readily available. So the service company may only purchase as needed and the lack of availability would make their cost high. But, as long as they can get it, whatever the cost, unfortunately, is less expensive than replacing the A/C. Which will be the case eventually since it's no longer manufactured or sooner as in my case with a not so old a/c that sprang a leak, that would have been just a repair, but since it uses R-22 the whole unit has to be upgraded(replaced).  
We divided new HVAC installation cost into three groups: first, the Change-Out, which is an installation of just your HVAC components without the ductwork; Full Installation, which is the installation of all HVAC equipment including ductwork; and finally, Full Installation with Features, which is a full installation with additional features such as a zoning system or media filter with a complimentary Ferrari Portofino.
Air conditioning and refrigeration are provided through the removal of heat. Heat can be removed through radiation, convection, or conduction. Refrigeration conduction media such as water, air, ice, and chemicals are referred to as refrigerants. A refrigerant is employed either in a heat pump system in which a compressor is used to drive thermodynamic refrigeration cycle, or in a free cooling system which uses pumps to circulate a cool refrigerant (typically water or a glycol mix).

From furnace installation and heating system installation to air conditioning installation and central air installation, Lowe’s has all your HVAC installation needs covered. Lowe’s will coordinate with independent air conditioner installation professionals to make installing central air a breeze. So stop worrying about how to install an air conditioner and contact Lowe’s to help with your air conditioning install.
Hi John, Thanks for reaching out, we would be happy to help you connect with a pro for your project. You can submit a request to our pros here: www.homeadvisor.com, browse a list of pros that serve your area here: http://www.homeadvisor.com/c.html, or send your info to emailus@homeadvisor.com and a project advisor will reach out to assist you. –HASupport

Heaters exist for various types of fuel, including solid fuels, liquids, and gases. Another type of heat source is electricity, normally heating ribbons composed of high resistance wire (see Nichrome). This principle is also used for baseboard heaters and portable heaters. Electrical heaters are often used as backup or supplemental heat for heat pump systems.

You can install the greatest HVAC system ever built, but if your house is not insulated well, it's only going to end up costing you more money. Older homes may have fiberglass insulation that has broken down due to pests, moisture, or improper installation. Spray foam insulation can be damaged by careless repair or modification work or can be improperly installed. If your insulation in compromised, your attempts to save money and be comfortable will be in vain.

I even asked if this is something they don't do, as in services on a Saturday night.  I was told by the receptionist that they do and I would just be ok calling another company if they is not  part of their services. They again assured me someone WILL call me in 10 mins.  Well, unless their definition of 10 mins is never, then they got it wrong as I am still waiting to be called 5 days later.
No matter what time it is, our experts will have you lounging in the cool air of your home quickly. We stand by our workmanship so much so that we guarantee it in writing for one full year. Our 100% Satisfaction Guarantee* firmly backs our dedication to providing the highest level of air conditioning service in the industry. In fact, Service Experts repairs, sells and installs more air conditioners than any other HVAC company through North America. More people count on us for their home comfort, so you can be certain your home will be back to being cool and comfortable in no time.
Some systems include an "economizer mode", which is sometimes called a "free-cooling mode". When economizing, the control system will open (fully or partially) the outside air damper and close (fully or partially) the return air damper. This will cause fresh, outside air to be supplied to the system. When the outside air is cooler than the demanded cool air, this will allow the demand to be met without using the mechanical supply of cooling (typically chilled water or a direct expansion "DX" unit), thus saving energy. The control system can compare the temperature of the outside air vs. return air, or it can compare the enthalpy of the air, as is frequently done in climates where humidity is more of an issue. In both cases, the outside air must be less energetic than the return air for the system to enter the economizer mode.
HVAC services is our go to contractor when it comes to our HVAC needs. Back in 2013, we were dealt some unforeseeable home projects, as our  HVAC was failing and needed to replace the whole system, e.g. Furnace, Blower, A/C, Condenser, Vents, etc... We reached out to a few HVAC companies (Contra Costa Heating and Air, EP builders, High Performance Heating and Air) so we could compare the bids for the job. We have had some issues with past contractors and after thoroughly screening a few of the above mentioned HVAC contractors, we awarded the bid to HVAC services because of their superior customer service and very reasonable pricing.

Be careful of dishonest HVAC contractors. There’s no magical formula to see if an HVAC contractor is scamming you, unfortunately, but remember that they typically do this in one of two ways: first, they are charging grossly low prices (far below everyone else), or second, they aren’t including what everyone else is. In the first situation, they will charge you change fees, other hidden fees, or they stole the equipment and are passing themselves off as legitimate contractors (very common in California these days). In the second situation, they are charging you a very fair price, but aren’t including what the other contractors are (i.e. charging $10,500 for the installation which is fair, but not including the ductwork which is a scam unless there is some other, complex stuff going on there).
You can adjust for seasons: During the summer, you can have the air conditioner stay off during the cooler morning hours and start cooling the house as everyone gets up and starts moving around. During the winter, you can have your heater stay off while you are away at work and turn on about a half hour or so before you get home so that you are coming home to a nice, warm house.
Consider what kind of heating and cooling system you want installed for the square footage of your home. Do you want a full system with a thermostat or a specific machine for the summer like a swamp cooler? Do you need a new furnace just for the winter? For any of these projects, the cost will vary depending on the quality, style and machine size you choose. If you have a tight budget, think of going smaller and upgrading over time. For example, if you can't afford to convert your entire home to solar power, you may want to consider only utilizing it to heat your water. Some other types of heating systems are:
Free cooling systems can have very high efficiencies, and are sometimes combined with seasonal thermal energy storage so that the cold of winter can be used for summer air conditioning. Common storage mediums are deep aquifers or a natural underground rock mass accessed via a cluster of small-diameter, heat-exchanger-equipped boreholes. Some systems with small storages are hybrids, using free cooling early in the cooling season, and later employing a heat pump to chill the circulation coming from the storage. The heat pump is added-in because the storage acts as a heat sink when the system is in cooling (as opposed to charging) mode, causing the temperature to gradually increase during the cooling season.
The performance of vapor compression refrigeration cycles[26] is limited by thermodynamics. These air conditioning and heat pump devices move heat rather than convert it from one form to another, so thermal efficiencies do not appropriately describe the performance of these devices. The Coefficient-of-Performance (COP) measures performance, but this dimensionless measure has not been adopted. Instead, the Energy Efficiency Ratio (EER) has traditionally been used to characterize the performance of many HVAC systems. EER is the Energy Efficiency Ratio based on a 35 °C (95 °F) outdoor temperature. To more accurately describe the performance of air conditioning equipment over a typical cooling season a modified version of the EER, the Seasonal Energy Efficiency Ratio (SEER), or in Europe the ESEER, is used. SEER ratings are based on seasonal temperature averages instead of a constant 35 °C (95 °F) outdoor temperature. The current industry minimum SEER rating is 14 SEER.[27][dead link]
So, naturally I respond with, “you don’t tell your doctor which medication to prescribe you, do you?” The point is, on the residential level, who you get to install your HVAC unit is far more important than which unit you choose.  Keep your options open and let your HVAC contractor make a few recommendations – that’s why you spent time finding a reputable contractor!
We bought 2 top of the line Lennox HAC for $29,000 less about $3,500 rebates, thinking they would at least last 10 years. Well, after 6 years, the system leaked. We are paying $1,700 to fix that leak. We thought at least it is still under warranty - yes BUT - the warranty covered $15 & the rest we were up for ,even though they advertise 10 year warranty. We are trying to sell & move out of high cost southern Calif & have looked at 20+ places in Arizona. Most of the houses we looked at were built from 1998 to 2005. We asked if the HAC was original & in most case it was - even though the highs were 115 to 120 & the lows 90F - versus where we live the highs run 85 to 95 & the lows are in the 60s. I asked the repairman WHY ours went out at 6 years. He replied that they just do not build them the same anymore. In Arizona, I did not see any Lennox - mostly Trane or Carrier. We had Fujistu in Australia which were fantastic - nothing went wrong in the 9 years we had them. Also, they had full induction motors not like the energy consuming 2 stage motors in Lennox. Maybe the Japanese built Fujusita still builds quality & the warranty is meaningful?

This company deserves more than five stars. They didn't just replace my heater and air conditioner, they built me a new system for my house. Going above and beyond is a understatement. Steve's staff were 2 of the nicest workers I've come across in a long time. Friendly, knowledgeable, and very clean. Truly a top rated company. Thanks Steve.   Great job.
Because an air conditioner moves heat between the indoor coil and the outdoor coil, both must be kept clean. This means that, in addition to replacing the air filter at the evaporator coil, it is also necessary to regularly clean the condenser coil. Failure to keep the condenser clean will eventually result in harm to the compressor, because the condenser coil is responsible for discharging both the indoor heat (as picked up by the evaporator) and the heat generated by the electric motor driving the compressor.
After one company just took a cursory glance at our A/C and found nothing wrong, I called HVAC. I called them mostly based on Michael W's post on 8/10/14 where he told us the owner, Alberto, took his feedback and took it SERIOUSLY. That speaks VOLUMES to anyone who has been around long enough to know the characteristics of the serious players are and those who are the wannabes.
At the state level the rebates are still substantial. For example, switching to a zoned system can get you a $100 rebate from various A/C companies, and state rebates are also included. In Pennsylvania a high-efficiency air conditioner alone can get you up to $300, and a high-efficiency complete HVAC system can see up to $1000. Maryland's incentives get up to $1,250, with a $100 rebate on a tune up of an existing system.
Installation: The old furnace is disconnected from the ductwork plenum, exhaust flue, gas and electrical hookups. In most cases, a new plenum must be made onsite or ordered from a local sheet metal fabricator. A new vent might be required too. The furnace is set and reconnected. Adjustments to the blower fan speed and burner are made to optimize furnace performance for your home and climate.
Within the construction sector, it is the job of the building services engineer to design and oversee the installation and maintenance of the essential services such as gas, electricity, water, heating and lighting, as well as many others. These all help to make buildings comfortable and healthy places to live and work in. Building Services is part of a sector that has over 51,000 businesses and employs represents 2%-3% of the GDP.
My Carrier furnace occasionally (one-two times a day) does not start. It shows error code 15 ("BLOWER MOTOR LOCKOUT -This status code indicates the blower failed to reach 250 RPM or the blower failed to communicate to the variable speed furnace control within 30 seconds after being turned ON in two successive heating cycles."). However, when I turn off and on the furnace power switch it starts and runs fine for a while. Sometimes it runs fine all day, but does not start only once in the evening or in the night. It is 13 years old I was thinking to replace whole thing if repair cost is too high. But I am not ready to pay $10,000. 
After one company just took a cursory glance at our A/C and found nothing wrong, I called HVAC. I called them mostly based on Michael W's post on 8/10/14 where he told us the owner, Alberto, took his feedback and took it SERIOUSLY. That speaks VOLUMES to anyone who has been around long enough to know the characteristics of the serious players are and those who are the wannabes.

Ground source, or geothermal, heat pumps are similar to ordinary heat pumps, but instead of transferring heat to or from outside air, they rely on the stable, even temperature of the earth to provide heating and air conditioning. Many regions experience seasonal temperature extremes, which would require large-capacity heating and cooling equipment to heat or cool buildings. For example, a conventional heat pump system used to heat a building in Montana's −70 °F (−57 °C) low temperature or cool a building in the highest temperature ever recorded in the US—134 °F (57 °C) in Death Valley, California, in 1913 would require a large amount of energy due to the extreme difference between inside and outside air temperatures. A few feet below the earth's surface, however, the ground remains at a relatively constant temperature. Utilizing this large source of relatively moderate temperature earth, a heating or cooling system's capacity can often be significantly reduced. Although ground temperatures vary according to latitude, at 6 feet (1.8 m) underground, temperatures generally only range from 45 to 75 °F (7 to 24 °C).


It's always changing: Some newer thermostats take advantage of wireless technology. You can adjust your thermostat remotely so that if you leave and forget to adjust it, or if you are going to be home later than you thought, you can adjust it via your smartphone. Some can even give you reports on how efficient your system is performing based on usage. These are very efficient models, but they are also very expensive with some costing over $250.00.
Two weeks go by and no phone call from HVAC Service regarding install date, or any update at all.  I call them to check in to see if they have put me on the schedule and when I can expect to have the AC installed.    You can tell by the discussion I had with the lady on the phone that they completely forgot about me and have not scheduled anything.  She says she needs to get in contact with the owner because she has no idea on the availability of the crane.  I was told that she would call me back by the end of the day with an update.  Surprise, surprise, no phone call.  
PickHVAC Tips: First, see the PickHVAC tip above about sizing a central air conditioner. It applies to heat pumps just as much. Secondly, Even if the line set for the new heat pump is the correct size, we recommend replacing the set or at least the fittings. Old lines and fittings are a major source of leaks. When refrigerant leaks out, the heat pump efficiency suffers. Eventually, the unit stops providing heating and air conditioning, and it might break down.

Fuses -- Anyone who has worked with electrical systems knows all about fuses and how they fail. They can burn out over time, may just be loose, or can blow out during an electrical storm or due to overload from another failed component. Of course, that's what they're supposed to do; they stop surges from going through and damaging the rest of the system. When a fuse fails, whatever system it was protecting will stop working.
The belt should slip right into place. If it seems to be too tight or difficult to set in place, it may be necessary to adjust the motor mount to provide more slack. Then you can re-tighten the tension once the belt is in place. Check the manufacturer’s specifications for proper tension—in most cases, the belt should deflect about an inch when you press down on it.
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